How to Get Rid of Mould in the Shower

First, work out what kind of mould you have

Not all shower mould is the same job. Before you reach for a product, look closely at where it is.

Surface mould on grout and tiles. Grey, black or pinkish marks sitting on the surface of the grout lines, often worst in the corners and along the bottom rows. This usually cleans off, or at least fades a long way, with the steps below.

Mould in or behind the silicone. Black spots or streaks inside the flexible sealant where the walls meet the floor, around the screen and along the vanity or bath edge. Once mould has grown into silicone, cleaning rarely removes it. The long-term fix is to replace the silicone.

Mould on the ceiling and upper walls. A spread of dark spots on painted surfaces above the tiles. This is almost always a ventilation problem, and cleaning alone will not stop it returning.

Before you start: safety

• Ventilate. Open the window and door and run the exhaust fan throughout.
• Protect yourself. Wear rubber gloves and eye protection. Some people also prefer a mask when scrubbing.
• Never mix products. Bleach mixed with ammonia, or with acidic cleaners such as vinegar, releases toxic gas. Use one product, rinse thoroughly, and only then try another.
• Check your surfaces. Acids such as vinegar etch natural stone — marble, travertine and limestone. On stone, use a pH-neutral stone cleaner and test anything new on a hidden patch first.
• Take care if you are sensitive. Anyone with asthma, allergies or a respiratory condition may be better off letting someone else do the scrubbing.

How to clean shower mould: step by step

1. Dry the area. Run the fan or leave the window open for a while so the tiles are dry. Cleaning products work better on a dry surface and are not diluted by water on the tiles.

2. Start mild for light mould.

• White vinegar: spray undiluted vinegar onto the affected grout (not on natural stone), leave it for around an hour, then scrub with a stiff grout brush or an old toothbrush.
• Bicarb paste: mix bicarbonate of soda with a little water into a thick paste, work it into the grout lines, leave it for ten to fifteen minutes and scrub. Bicarb is mildly abrasive, which helps lift staining.

Rinse well with warm water once you have finished.

3. Step up for stubborn staining on grout. If marks remain, use a bathroom mould remover or a diluted bleach product, following the label's dilution and contact time. Apply it to the grout only, leave it for the recommended time, then rinse thoroughly. Keep bleach away from coloured grout you want to keep — it can lighten it — and never use it straight after vinegar without rinsing first.

4. Treat the silicone honestly. Spray the silicone, leave it, and scrub gently. If the black marks are still visible after a proper clean, the mould is inside the sealant. Scrubbing harder will not help.

5. Dry everything. Squeegee the walls, towel-dry the joints and leave the fan running until the room is dry.

For a full routine on tiles and grout beyond mould — including general cleaning and resealing — a dedicated tile and grout cleaning guide is worth following. Soap scum is a different problem again and needs its own approach.

Replacing mouldy silicone

When mould has grown into the sealant, replacing it is the lasting fix:

1. Cut out the old silicone with a sharp blade or a sealant removal tool, taking care not to scratch the tiles or screen.
2. Remove every trace of residue. New silicone will not bond to old silicone or to soap film.
3. Clean the joint with a mould product, rinse, and let it dry completely — ideally overnight with the fan running.
4. Apply a bathroom-grade, mould-resistant sealant in a continuous bead and tool it smooth.
5. Leave the shower unused for the curing time on the product, usually a day.

If the grout itself is crumbling, cracked or missing, cleaning will not help either. Regrouting, or a professional repair, is the next step.

How to stop mould coming back

Mould needs moisture and time. Take either away and it struggles.

• Run the exhaust fan during and after every shower. A fan that stops the moment you leave is not enough. A run-on timer or humidity sensor keeps it going until the room is dry. Our guide to bathroom exhaust fans covers sizing, ducting and controls.
• Squeegee after showering. Thirty seconds on the walls and screen removes most of the water mould needs.
• Leave the screen door open and hang wet towels outside the shower.
• Clean little and often. A quick weekly wipe stops spores establishing in the grout.
• Seal cement-based grout periodically, as recommended by the grout manufacturer, so it absorbs less water.
• Fix drips and leaks promptly. A dripping tap or a slow leak keeps surfaces constantly wet.

When mould signals a bigger problem

Sometimes mould is a symptom rather than the problem. Get it looked at if you notice:

• Mould that returns within days, however well you clean.
• Mould spreading across the ceiling or up the walls, not just in the shower.
• Swelling or delamination in the vanity, door frame or skirting.
• A persistent musty smell, even when the room looks clean.
• Loose or hollow-sounding tiles, cracked grout at the base of the walls, or stains in the room next door or the unit below.

These usually point to either poor ventilation or water escaping the shower through failed waterproofing. A leaking shower is its own diagnosis, and it is worth getting right before the damage spreads into the framing or the floor.

When a renovation is the fix

If the fan has never worked, the silicone keeps failing and there are signs of water behind the tiles, a renovation that fixes the waterproofing and the extraction together is often the lasting answer. See our bathroom renovations page for how that runs, and our cost guide for broad planning figures. If you are in or around Parramatta, we can take a look when we measure up.